Electric wire twisting device and electric wire twisting method

ABSTRACT

An electric wire twisting device is provided, which is capable of producing a preferable twisted electric wire from a plurality of electric wires of which both ends are cut. An electric wire twisting device  1  includes a first gripping device  11  including a first clamp  2   a  that grips a first end of a first electric wire CT, a second clamp  2   b  that grips a first end of a second electric wire C 2,  and a first holder  15 A that holds the first clamp  2   a  and the second clamp  2   b.  The electric wire twisting device  1  includes a second gripping device  12  that grips a second end of the first electric wire CT and a second end of the second electric wire CT, a first revolving actuator  3   b  that causes the first holder  15 A to rotate around a center line of revolution CL, and a first rotating actuator  3   a  that causes the first clamp  2   a  and the second clamp  2   b  to rotate around a center line of rotation that is parallel to the center line of revolution CL or is inclined with respect to the center line of revolution CL.

TECHNICAL FIELD

The present invention relates to an electric wire twisting device and anelectric wire twisting method for twisting a plurality of electricwires.

BACKGROUND ART

Conventionally, an electric wire twisting device and an electric wiretwisting method for twisting a plurality of electric wires are known.For example, Patent Literature 1 discloses an electric wire twistingdevice for twisting a first electric wire wound around a first bobbinand a second electric wire wound around a second bobbin. In thiselectric wire twisting device, the first and second electric wires aretwisted while pulling out the first electric wire from the first bobbinand pulling out the second electric wire from the second bobbin.

Patent Literature 2 discloses an electric wire twisting device includinga first clamp that grips one end of a first electric wire, a secondclamp that grips one end of a second electric wire, and a third clampthat grips the other set of ends of the first and second electric wires.In this electric wire twisting device, the first and second clamps arerotated collectively to twist the first and second electric wires in astate in which the third clamp is fixed. In this specification, rotatingthe first and second clamps collectively is referred to as “revolution”.Rotating the first and second clamps independently is referred to as“rotation”. In the electric wire twisting device disclosed in PatentLiterature 2, the first and second clamps are rotated in a directionopposite to the direction of revolution during the revolution so thatthe respective electric wires themselves are not twisted during thetwisting.

CITATION LIST Patent Literature

-   Patent Literature 1: Japanese Patent Application Publication No.    H02-44615-   Patent Literature 2: Japanese Patent Application Publication No.    2009-129729

SUMMARY OF INVENTION Technical Problem

In the electric wire twisting device of Patent Literature 1, bothelectric wires are twisted while being pulled out. In order to obtain atwisted electric wire having a desired length, cutting the twistedelectric wire after twisting is necessary. However, cutting a pair ofelectric wires after twisting is complicated.

In the electric wire twisting device of Patent Literature 2, a twistedelectric wire can be produced from a pair of electric wires of whichboth ends are cut in advance. However, in the electric wire twistingdevice of Patent Literature 2, rotating mechanisms that rotate the firstand second clamps, respectively, and a devolving mechanism that rotatesthe first and second clamps collectively are driven by the same motor.Due to this, it is not possible to operate the rotating mechanisms andthe revolving mechanism independently. Various kinds of wires havingvarious diameters or hardness are to be twisted. With respect to anelectric wire having a core and a covering, there are various kinds ofelectric wires which have same diameter but different coveringthicknesses. In the electric wire twisting device disclosed in PatentLiterature 2, it is impossible to control rotation and revolutionindependently in accordance with the specification of each types ofvarious electric wires. Therefore, there is a case in which it is notpossible to twist a plurality of electric wires appropriately so thatthe twisted electric wire has desired impedance characteristics.

In view of the above-described problems, an object of the presentinvention is to provide an electric wire twisting device and an electricwire twisting method capable of producing an appropriate twistedelectric wire from a plurality of electric wires of which both ends arecut.

Solution to Problem

An electric wire twisting device according to the present invention isan electric wire twisting device producing a twisted electric wire bytwisting at least a first electric wire and a second electric wire, eachof the first and second electric wires having a first end and a secondend. The electric wire twisting device includes a first gripping deviceincluding a first clamp that grips the first end of the first electricwire, a second clamp that grips the first end of the second electricwire, and a first holder that holds the first clamp and the secondclamp. The electric wire twisting device includes a second grippingdevice that grips the second end of the first electric wire and thesecond end of the second electric wire; a first revolving actuator thatis connected to the first holder and causes the first holder to rotatearound a center line of revolution positioned between the first clampand the second clamp; and a first rotating actuator that is connected toat least the first clamp and causes the first clamp to rotate around afirst center line of rotation that is parallel to the center line ofrevolution or is inclined with respect to the center line of revolution.

An electric wire twisting method according to the present invention isan electric wire twisting method of twisting at least a first electricwire and a second electric wire, each of the first and second electricwires having a first end and a second end. The electric wire twistingmethod includes a gripping step of gripping the first end of the firstelectric wire and the first end of the second electric wire and grippingthe second end of the first electric wire and the second end of thesecond electric wire; a revolving step of rotating the first ends of thefirst and second electric wires collectively and/or the second ends ofthe first and second electric wires collectively; and a rotating step ofrotating the first ends of the first and second electric wiresindependently and/or rotating the second ends of the first and secondelectric wires independently. The rotating step starts after therevolving step starts.

Advantageous Effects of Invention

According to the present invention, it is possible to produce anappropriate twisted electric wire from a plurality of electric wires ofwhich both ends are cut.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of an electric wire twisting deviceaccording to a first embodiment.

FIG. 2 is a perspective view of the electric wire twisting device afterelectric wires are twisted.

FIG. 3 is a side view of a twisted electric wire.

FIG. 4 is a partially sectioned plan view of a first gripping device.

FIG. 5 is a partially enlarged cross-sectional view of the firstgripping device when a grip arm is open.

FIG. 6 is a block diagram of a controller or the like of the electricwire twisting device.

FIG. 7 is a flowchart of an electric wire twisting method.

FIG. 8 is a timing chart of a rotating step S2 and a revolving step S3.

FIG. 9 is a timing chart of a rotating step S2 and a revolving step S3according to a modification.

FIG. 10 is a timing chart of a rotating step S2 and a revolving step S3according to a modification.

FIG. 11 is a side view of a twisted electric wire after a rotating stepS4 is performed.

FIG. 12 is a timing chart of a revolving step S3 and a rotating step S4.

FIG. 13 is a timing chart of a revolving step S3 and a rotating step S4according to a modification.

FIG. 14 is a timing chart of a revolving step S3 and a rotating step S4according to a modification.

FIG. 15 is a timing chart of a revolving step S3 and a rotating step S4according to a modification.

FIG. 16 is a timing chart of a revolving step S3 and a rotating step S4according to a modification.

FIG. 17 is a perspective view of an electric wire twisting deviceaccording to a modification.

FIG. 18 is a schematic diagram of the electric wire twisting deviceaccording to the first embodiment.

FIG. 19 is a schematic diagram of an electric wire twisting deviceaccording to a modification.

FIG. 20 is a schematic diagram of an electric wire twisting deviceaccording to a modification.

FIG. 21 is a schematic diagram of an electric wire twisting deviceaccording to a second embodiment.

FIG. 22 is a schematic diagram of an electric wire twisting deviceaccording to a modification.

FIG. 23 is a schematic diagram of an electric wire twisting deviceaccording to a modification.

FIG. 24 is a perspective view of an electric wire twisting device havinga pitch measuring device.

FIG. 25 is a schematic top view of a portion of a twisted electric wire.

FIG. 26 is a schematic diagram illustrating a state in which a twistedelectric wire is inclined with respect to a moving direction of a movingunit.

FIG. 27 is a schematic top view of a twisted electric wire when agripping device is oriented vertically.

FIG. 28 is a perspective view of a pitch measuring device including aphotoelectric sensor that emits light in a strip-like shapeperpendicular to a moving direction of a moving unit.

FIG. 29 is a perspective top view of the pitch measuring deviceillustrated in FIG. 28.

FIG. 30 is a perspective view of a pitch measuring device including aplurality of sets of moving units and pitch measuring sensors.

FIG. 31 is a perspective view of a moving unit having a sensorattachment member.

FIG. 32 is a perspective view of a moving unit having a shielding plate.

DESCRIPTION OF EMBODIMENTS First Embodiment

Hereinafter, an embodiment of the present invention will be describedwith reference to the drawings. As illustrated in FIGS. 1 and 2, anelectric wire twisting device (hereinafter referred to simply as atwisting device) 1 according to an embodiment of the present inventionis a device that twists two electric wires C1 and C2 (hereinafter, theelectric wires C1 and C2 will be referred to as a first electric wireand a second electric wire, respectively). As illustrated in FIG. 3,each of the electric wires C1 and C2 has a core 71 and a covering 72that covers the core 71. The core 71 is formed of a conductor such asmetal or the like and the covering 72 is formed of an insulator such asa vinyl resin or the like. The edges of both electric wires C1 and C2may be processed. For example, as illustrated in FIG. 3, the coverings72 at the ends of both electric wires C1 and C2 may be stripped.Moreover, terminals (not illustrated) may be pressure-joined to the endsof both electric wires C1 and C2.

As illustrated in FIG. 1, the twisting device 1 includes a rail 4 and afirst gripping unit 51 and a second gripping unit 52 supported by therail 4. At least one of the first and second gripping units 51 and 52 isslidably supported by the rail 4. In the present embodiment, the firstgripping unit 51 is slidably supported by the rail 4. However, thesecond gripping unit 52 may be slidably supported by the rail 4. Boththe first and second gripping units 51 and 52 may be slidably supportedby the rail 4.

In the following description, symbols F and Rr in the drawings indicatethe front and rear, respectively. However, these directions aredetermined for the sake of convenience only and do not restrict anactual installation of the twisting device 1. The rail 4 extends in afront-rear direction. The first gripping unit 51 is located forward ofthe second gripping unit 52.

The first and second electric wires C1 and C2 each have a front end anda rear end. Here, the front end and the rear end are examples of a“first end” and a “second end”, respectively. The first gripping unit 51includes a first gripping device 11 that grips the front end of thefirst electric wire C1 and the front end of the second electric wire C2.The first gripping device 11 includes a first clamp 2 a that grips thefront end of the first electric wire C1, a second clamp 2 b that gripsthe front end of the second electric wire C2, and a first holder 15Athat holds the first and second clamps 2 a and 2 b. The second grippingunit 52 includes a second gripping device 12 that grips the rear end ofthe first electric wire C1 and the rear end of the second electric wireC2. The second gripping device 12 includes a third clamp 2 c that gripsthe rear end of the first electric wire C1, a fourth clamp 2 d thatgrips the rear end of the second electric wire C2, and a second holder15B that holds the third and fourth clamps 2 c and 2 d.

First, a configuration of the first gripping unit 51 will be described.The first gripping unit 51 includes a base 5 that engages with the rail4 and a unit body 7 that is supported by the base 5. The unit body 7 hasa vertical plate 7 a and a vertical plate 7 b. The vertical plate 7 a islocated in front of the vertical plate 7 b. A first motor 3 a and asecond motor 3 b are fixed to a front portion of the vertical plate 7 a.The first and second motors 3 a and 3 b are examples of a “firstrotating actuator” and a “first revolving actuator”, respectively. Arotating shaft 8 connected to the first motor 3 a passes through thevertical plates 7 a and 7 b. A gear 18 is fixed to a rear end of therotating shaft 8. The gear 18 is located rearward of the vertical plate7 b. A gear 13 is located below the gear 18, and a driving gear 14 islocated below the gear 13. The gear 13 engages with the gear 18, and afront portion of the driving gear 14 engages with the gear 13. A firstgear 16 and a second gear 17 are located on lateral sides of the rearportion of the driving gear 14. The driving gear 14 is located betweenthe first and second gears 16 and 17. The rear portion of the drivinggear 14 is configured as a tapered gear. The rear portion of the drivinggear 14 engages with the first and second gears 16 and 17.

FIG. 4 is a plan view of the first gripping unit 51 illustrating aportion of the first gripping unit 51 in a sectioned state. Asillustrated in FIG. 4, the first and second gears 16 and 17 areconfigured as a tapered gear. The first and second clamps 2 a and 2 beach have a shaft 20, a compression spring 23, a pair of grip arms 22,and a link 21 that connects the shaft 20 and the grip arm 22. The link21 has a first link bar 21 a and a second link bar 21 b rotatablyconnected to the first link bar 21 a. The shaft 20 of the first clamp 2a passes through the first gear 16 and the first holder 15A. The shaft20 of the first clamp 2 a is supported by the first gear 16 and thefirst holder 15A so as to be movable in an axial direction of the shaft20. The shaft 20 of the first clamp 2 a is supported by the first gear16 so as not to be rotatable to the first gear 16 and rotatablysupported by the first holder 15A. The shaft 20 of the second clamp 2 bpasses through the second gear 17 and the first holder 15A. The shaft 20of the second clamp 2 b is supported by the second gear 17 and the firstholder 15A so as to be movable in the axial direction of the shaft 20.The shaft 20 of the second clamp 2 b is supported by the second gear 17so as not to be rotatable to the second gear 17 and rotatably supportedby the first holder 15A. In the present embodiment, a center line Q1 ofthe shaft 20 of the first clamp 2 a is a “first center line ofrotation”, and a center line Q2 of the shaft 20 of the second clamp 2 bis a “second center line of rotation”.

A pressure receiving portion 20 a having a larger outer diameter thanthe shaft 20 is provided in a base end of the shaft 20 of each of thefirst and second clamps 2 a and 2 b. The distal end of the shaft 20 ofeach of the first and second clamps 2 a and 2 b is connected to thefirst link bar 21 a of the link 21. The grip arm 22 is connected to thedistal end of the shaft 20 via the link 21. The shaft 20 and the griparm 22 are connected so that the grip arm 22 is open when the shaft 20moves from the base end toward the distal end and the grip arm 22 isclosed when the shaft 20 moves from the distal end toward the base end.The compression spring 23 of the first clamp 2 a is disposed between thefirst gear 16 and the pressure receiving portion 20 a of the shaft 20.The compression spring 23 of the second clamp 2 b is disposed betweenthe second gear 17 and the pressure receiving portion 20 a of the shaft20. The shaft 20 is pulled toward the base end by the compression spring23. The compression spring 23 provides the grip arm 22 with a force toclose.

A clamp actuator 24 is located between the vertical plates 7 a and 7 b.The clamp actuator 24 is configured to generate force that presses theshaft 20 from the base end toward the distal end. In the presentembodiment, the clamp actuator 24 is configured as an air cylinder.However, the clamp actuator 24 is not limited to an air cylinder but maybe other actuators such as a motor. The clamp actuator 24 includes acylinder 24 a, a rod 24 b, and a pressing portion 24 c provided at adistal end of the rod 24 b. When the clamp actuator 24 is turned on, therod 24 b is extended, and the pressing portion 24 c presses the pressurereceiving portion 20 a of the shaft 20 as illustrated in FIG. 5. In thisway, the grip arm 22 is open. On the other hand, when the clamp actuator24 is turned off, the rod 24 b is contracted, and the pressing portion24 c is separated from the pressure receiving portion 20 a of the shaft20. As a result, the shaft 20 is pulled toward the base end by the forceof the compression spring 23 and the grip arm 22 is closed (see FIG. 4).

As illustrated in FIG. 1, the rotating shaft 9 connected to the secondmotor 3 b passes through the vertical plates 7 a and 7 b. The rotatingshaft 9 passes through the driving gear 14 and is fixed to the firstholder 15A (see FIG. 4). The rotating shaft 9 is rotatable with respectto the driving gear 14. The first holder 15A rotates together with therotating shaft 9. In the present embodiment, the center line CL of therotating shaft 9 is a “center line of revolution”.

In the present embodiment, as illustrated in FIG. 4, the first andsecond center lines of rotation Q1 and Q2 are tilted from the centerline of revolution CL. The shaft 20 of each of the first and secondclamps 2 a and 2 b is inclined with respect to the center line ofrevolution CL such that a portion of the shaft 20 comes close to thecenter line of revolution CL as the portion of the shaft 20 comes closeto the distal end. The first and second clamps 2 a and 2 b are disposedsuch that a portion of them come close to the center line of revolutionCL as the portion of them come close to the distal end. The grip arm 22of each of the first and second clamps 2 a and 2 b is disposed such thata portion of the grip arm 22 come close to the center line of revolutionCL as the portion of the grip arm 22 come close to the distal end.

For example, by driving the first motor 3 a and stopping the secondmotor 3 b, it is possible to rotate the first and second clamps 2 a and2 b. That is, it is possible to cause the first and second clamps 2 aand 2 b to rotate. Here, the rotation of the first clamp 2 a around thefirst center line of rotation Q1 and the rotation of the second clamp 2b around the second center line of rotation Q2 will be referred to as“rotation”. Specifically, when the first motor 3 a is driven, therotating shaft 8 rotates. When the rotating shaft 8 rotates, the gear 18rotates. When the gear 18 rotates, the gear 13 rotates. When the gear 13rotates, the driving gear 14 rotates. In this way, the driving gear 14is connected to the first motor 3 a via the gears 13 and 18 and therotating shaft 8. The driving gear 14 rotates by receiving the drivingforce of the first motor 3 a. Since the first and second gears 16 and 17are engaged with the driving gear 14, when the gear 18 rotates, thefirst and second gears 16 and 17 rotate. Therefore, the shafts 20 of thefirst and second clamps 2 a and 2 b rotate, whereby the grip arms 22 ofthe first and second clamps 2 a and 2 b rotate. In the presentembodiment, the first motor 3 a, the rotating shaft 8, and the gears 13to 18 form a “rotation driving mechanism” that rotates the first andsecond clamps 2 a and 2 b.

When the second motor 3 b is driven, the first holder 15A rotates andthe first gripping device 11 rotates. When the first gripping device 11rotates, the first and second clamps 2 a and 2 b rotate collectively.Therefore, driving the second motor 3 b makes it possible to cause thefirst and second clamps 2 a and 2 b to revolve. Here, rotation of thefirst and second clamps 2 a and 2 b around the center line of revolutionCL will be referred to as “revolution”. Specifically, when the secondmotor 3 b is driven, the rotating shaft 9 rotates. Since the rotatingshaft 9 is fixed to the first holder 15A, when the rotating shaft 9rotates, the first holder 15A rotates. Since the first and second clamps2 a and 2 b are held by the first holder 15A, the first and secondclamps 2 a and 2 b rotate collectively according to rotation of thefirst holder 15A. In the present embodiment, the second motor 3 b andthe rotating shaft 9 form a “revolution driving mechanism” that rotatesthe first gripping device 11.

The first gripping unit 51 includes a moving device 6 having a motor orthe like that moves the base 5 along the rail 4. The configuration ofthe moving device 6 is not particularly limited and various knowndevices can be used. For example, although not illustrated in thedrawings, the moving device 6 may include a power transmission beltconnected to the base 5, a pulley wound around the power transmissionbelt, and a motor connected to the pulley. A driving source is notlimited to a motor. An air cylinder, a spring, and the like can be usedas the driving source.

Hereinabove, the configuration of the first gripping unit 51 has beendescribed. The second gripping unit 52 has the same configuration as thefirst gripping unit 51 except that the base 5 is fixed to the rail 4 soas to be immovable. The second gripping unit 52 and the first grippingunit 51 have a symmetric configuration in relation to the front-reardirection. The second gripping unit 52 includes a third clamp 2 c,afourth clamp 2 d,a second holder 15B, a third motor 3 c,and a fourthmotor 3 d instead of the first clamp 2 a, the second clamp 2 b, thefirst holder 15A, the first motor 3 a, and the second motor 3 b,respectively. The first clamp 2 a, the second clamp 2 b, the firstholder 15A, the first motor 3 a, and the second motor 3 b have the sameconfiguration as the third clamp 2 c,the fourth clamp 2 d,the secondholder 15B, the third motor 3 c,and the fourth motor 3 d,respectively.Since the other components are similar to those of the first grippingunit 51, and the same components will be denoted by the same referencenumerals, and the description thereof will be omitted.

The twisting device 1 includes a controller 30 that controls therevolution driving mechanism and the rotation driving mechanism. Thecontroller is communicably connected to the first to fourth motors 3 a,3 b, 3 c,and 3 d,the clamp actuators 24 of the first and second grippingunits 51 and 52, and the moving device 6 so as to control thesecomponents. The configuration of the controller 30 is not particularlylimited and is configured as a microcomputer, for example. Thecontroller 30 may include a CPU, a RAM, a ROM, and the like, forexample. The controller 30 may be a controller dedicated for thetwisting device 1 and may be a general-purpose controller such as apersonal computer.

As illustrated in FIG. 6, the controller 30 includes a grip control unit31, a first rotation control unit 32, a revolution control unit 33, anda second rotation control unit 34. These respective control units 31 to34 are realized by a computer executing a predetermined program. Theserespective control units 31 to 34 are configured as identical ordifferent processors.

Next, an example of an operation of the twisting device 1 will bedescribed with reference to the flowchart of FIG. 7. First, a grippingstep S1 is performed. In the gripping step S1, the grip control unit 31drives the clamp actuators 24 of the first and second gripping units 51and 52. In this way, the first and second gripping units 51 and 52 gripthe first and second electric wires C1 and C2, respectively.Specifically, the first clamp 2 a is open and closed so that the firstclamp 2 a grips the front end of the first electric wire C1. The secondclamp 2 b is open and closed so that the second clamp 2 b grips thefront end of the second electric wire C2. The third clamp 2 c is openand closed so that the third clamp 2 c grips the rear end of the firstelectric wire C1. The fourth clamp 2 d is open and closed so that thefourth clamp 2 d grips the rear end of the second electric wire C2. Inthis way, the first and second electric wires C1 and C2 are arranged inparallel (see FIG. 1).

Subsequently, a rotating step S2 is performed. In the rotating step S2,the first and third motors 3 a and 3 c are driven by the first rotationcontrol unit 32. By doing so, the rotating shaft 8 of the first motor 3a rotates in the direction R1 in FIG. 1. The rotating shaft 8 of thethird motor 3 c rotates in the direction R2 opposite to the directionR1. The first and second clamps 2 a and 2 b rotate in the direction R2,and the third and fourth clamps 2 c and 2 d rotate in the direction R1.In this way, the front end and the rear end of the first electric wireC1 rotate in the opposite directions and the front end and the rear endof the second electric wires C2 rotate in the opposite directions. As aresult, the first and second electric wires C1 and C2 are twistedindependently.

Subsequently, a revolving step S3 is performed. In the revolving stepS3, the revolution control unit 33 drives the second and fourth motors 3b and 3 d. By doing so, the rotating shaft 9 of the second motor 3 brotates in the direction R1, and the rotating shaft 9 of the fourthmotor 3 d rotates in the direction R2. In this way, the first and secondclamps 2 aand 2 b rotate collectively in the direction R1, and the thirdand fourth clamps 2 c and 2 d rotate collectively in the direction R2.The first to fourth clamps 2 a to 2 d revolve in a direction opposite tothe direction of rotation. In this way, the first and second electricwires C1 and C2 are twisted (see FIG. 2). When the first and secondelectric wires C1 and C2 are twisted, an apparent length (that is, thelength in the front-rear direction) of the electric wires C1 and C2decreases. Therefore, the controller 30 drives the moving device 6 tomove the base 5 of the first gripping unit 51 so that the distancebetween the first and second gripping units 51 and 52 decreases as thetwisting of the electric wires C1 and C2 progresses. When the first andsecond electric wires C1 and C2 are loosened in advance before therevolving step S3 is performed, it is not necessary to decrease thedistance between the first and second gripping units 51 and 52 in thecourse of the revolving step S3. In such a case, the moving device 6 isnot necessary. The moving device 6 is not essential but can be omitted.

As illustrated in FIG. 8, the revolving step S3 may start after therotating step S2 ends. t21 and t22 indicate the starting and ending timeof the rotating step S2, respectively. t31 and t32 indicate the startingand ending time of the revolving step S3, respectively. A horizontalaxis t indicates time. As illustrated in FIG. 8, t31 may be later thant22. The revolving step S3 may start simultaneously with the end of therotating step S2. That is, t22=t31. As illustrated in FIG. 9, therevolving step S3 may start after the rotating step S2 starts and beforethe rotating step S2 ends. That is, t21<t31<t22. As illustrated in FIG.10, the rotating step S2 and the revolving step S3 may be performedsimultaneously. The rotating step S2 and the revolving step S3 may startsimultaneously. That is, t21=t31. The rotating step S2 and the revolvingstep S3 may end simultaneously. That is, t22=t32. In this manner, therevolving step S3 may start simultaneously with or after the start ofthe rotating step S2, and the timings of the rotating step S2 and therevolving step S3 are not particularly limited.

In the twisting device 1, rotation is performed by the first and thirdmotors 3 a and 3 c and revolution is performed by the second and fourthmotors 3 b and 3 d. Rotation and revolution are performed by differentmotors. Due to this, the timings of rotation and revolution can be setindependently. The number of rotations and the number of revolutions canbe set independently. For example, the number of rotations may be set tobe smaller or larger than, or the same as the number of revolutions. Therotation speed of rotation and the rotation speed of revolution can beset independently. The timings of rotation and revolution, the number ofrotations and revolutions, and the rotation speed of rotation andrevolution may be changed according to the kind of the first and secondelectric wires C1 and C2. For example, the covering 72 (see FIG. 3) mayhave a different thickness depending on the kind of the first and secondelectric wires C1 and C2. Depending on the kind of the first and secondelectric wires C1 and C2, untwisting may occur due to elastic forceafter twisting. In such a case, control may be performed so that thenumber of rotations in the rotating step S2 is increased, for example.

The first and second clamps 2 a and 2 b are separated in a directionperpendicular to the longitudinal direction of the twisted electric wireCT. Similarly, the third and fourth clamps 2 c and 2 d are separated ina direction perpendicular to the longitudinal direction of the twistedelectric wire CT. In the state illustrated in FIG. 2, the first andsecond clamps 2 a and 2 b are separated in a left-right direction, andthe third and fourth clamps 2 c and 2 d are separated in the left-rightdirection. Therefore, it is not possible to twist the distal ends of thefirst and second electric wires C1 and C2. As illustrated in FIG. 3, thetwisted electric wire CT has a portion (hereinafter referred to as atwisted portion) Cs in which the first and second electric wires C1 andC2 are twisted and a portion (hereinafter referred to as a non-twistedportion) Cr in which the first and second electric wires C1 and C2 arenot twisted. Here, a portion in which the first and second electricwires C1 and C2 are in contact is the twisted portion Cs, and a portionin which the first and second electric wires C1 and C2 are not incontact is the non-twisted portion Cr.

As a result of intensive studies, the present inventors have found thatthe position of a terminal end Cc of the twisted portion Cs does notchange substantially even when the first and second clamps 2 a and 2 bare revolved further after the first and second clamps 2 a and 2 b arerevolved so that the first and second electric wires C1 and C2 aretwisted for a certain number of times. In this case, it has been foundthat the pitch (hereinafter also referred to as a twist pitch) P oftwisting of the twisted portion Cs decreases and the length (hereinafterreferred to as a residual twisting length) L of the non-twisted portionCr does not decrease substantially. Furthermore, it has been found thatalthough the number of twisting does not change when the first andsecond clamps 2 a and 2 b are rotated after the first and secondelectric wires C1 and C2 are twisted for a certain number of times, thelength of the twisted portion Cs changes and the residual twistinglength L changes. Specifically, it has been found that the residualtwisting length L increases when the first and second clamps 2 a and 2 bare rotated in the same direction as the revolution direction, and theresidual twisting length L decreases when the first and second clamps 2a and 2 b are rotated in a direction opposite to the revolutiondirection.

In this twisting device 1, based on the above-mentioned findings, therotating step S4 is performed after the revolving step S3 is performedin order to decrease the residual twisting length L of the twistedelectric wire CT. That is, the rotating step S4 is performed such thatthe first and second clamps 2 a and 2 b are rotated in a directionopposite to the revolution direction and the third and fourth clamps 2 cand 2 d are rotated in a direction opposite to the revolution direction.Specifically, after the revolution control unit 33 stops the second andfourth motors 3 b and 3 d,the second rotation control unit 34 drives thefirst and third motors 3 a and 3 c. The second rotation control unit 34drives the first motor 3 a so that the rotating shaft 8 of the firstmotor 3 a rotates in the direction R1 and drives the third motor 3 c sothat the rotating shaft 8 of the third motor 3 c rotates in thedirection R2. In this way, as illustrated in FIG. 11, the terminal endsCc of the first and second electric wires C1 and C2 move toward thedistal end and the residual twisting length L of the twisted electricwire CT decreases.

In the present embodiment, as illustrated in FIG. 12, the rotating stepS4 starts after the revolving step S3 ends. t41 and t42 indicate thestarting and ending time of the rotating step S4. Here, t32<t41.However, the rotating step S4 may start simultaneously with the end ofthe revolving step S3. That is, t32=t41. In the present embodiment, therotating step only is performed after the revolving step ends. Due tothis, it is possible to execute the rotating step S4 more stably. Thatis, by causing the first to fourth clamps 2 a to 2 d to rotate aftertwisting the first and second electric wires C1 and C2 by causing thefirst to fourth clamps 2 a to 2 d to revolve, it is possible to performan operation of adjusting the residual twisting length L of the twistedelectric wire CT more stably.

However, the timings of the revolving step S3 and the rotating step S4are not limited to the above-described timings The rotating step S4 maystart after the revolving step S3 starts, and the starting time t41 ofthe rotating step S4 is not necessarily limited to the time after theend of the revolving step S3. As illustrated in FIGS. 13 to 15, thestarting time t41 of the rotating step S4 may be earlier than the endingtime t32 of the revolving step S3. In this case, the ending time t42 ofthe rotating step S4 may be later (see FIG. 13) or earlier (see FIG. 14)than or the same as (see FIG. 15) the ending time t32 of the revolvingstep S3. In the examples illustrated in FIGS. 13 to 15, the revolvingstep S3 and the rotating step S4 have an overlapping period. In thisperiod, the first and second motors 3 a and 3 b are drivensimultaneously and the first and second clamps 2 a and 2 b rotate andrevolve. Similarly, the third and fourth motors 3 c and 3 d are drivensimultaneously and the third and fourth clamps 2 c and 2 d rotate andrevolve. As illustrated in FIG. 16, the rotating step S4 may beperformed after the revolving step S3 is performed and another revolvingstep S3 a may be performed simultaneously with at least a portion of therotating step S4.

According to the examples illustrated in FIGS. 13 to 15, since therevolving step S3 overlaps at least a portion of the rotating step S4,it is possible to shorten the entire period of the revolving step S3 andthe rotating step S4. Therefore, it is possible to produce asatisfactory twisted electric wire CT in a shorter period of time.

According to the example illustrated in FIG. 13, since the revolvingstep S3 overlaps a portion of the rotating step S4 and a remainingportion of the rotating step S4 is performed after the revolving step S3ends. Due to this, it is possible to shorten the entire period of therevolving step S3 and the rotating step S4 and to perform the rotatingstep S4 stably after the revolving step S3 ends.

Here, although a case in which the period (the period between t41 andt42) of the rotating step S4 is shorter than the period (the periodbetween t31 and t32) of the revolving step S3 has been described, theperiod of the rotating step S4 may be longer than or the same as theperiod of the revolving step S3.

When the rotating step S4 ends, a collecting step S5 of collecting thetwisted electric wire CT is performed. In the collecting step S5, thegrip control unit 31 drives the clamp actuators 24 of the first andsecond gripping units 51 and 52. By doing so, the first to fourth clamps2 a to 2 d are open and closed and the twisted electric wire CT iscollected. A method of collecting the twisted electric wire CT is notparticularly limited. For example, the electric wire twisting device mayinclude a gripping device (not illustrated) that grips the twistedelectric wire CT so that the twisted electric wire CT is delivered fromthe first and second gripping units 51 and 52 to the gripping device.When the first to fourth clamps 2 a to 2 d are open, the twistedelectric wire CT falls due to its own weight. A collection tray (notillustrated) may be provided below the rail 4 so that the twistedelectric wire CT is collected in the collection tray.

As described above, according to the twisting device 1 of the presentembodiment, it is possible to twist the first and second electric wiresC1 and C2 of which both ends are cut. It is not necessary to cut thetwisted electric wire CT after twisting both electric wires C1 and C2.Therefore, since it is not necessary to perform a complicated processafter twisting, it is possible to produce the twisted electric wire CTeasily. The twisting device 1 includes the first motor 3 a that causesthe first and second clamps 2 a and 2 b to rotate and the second motor 3b that causes the first and second clamps 2 a and 2 b to revolve.Therefore, it is possible to control rotation and revolutionindependently. For example, it is possible to adjust the timings ofrotation and revolution arbitrarily. Moreover, it is possible to adjustthe number of rotations or the rotation speed of rotation and revolutionarbitrarily. In this way, it is possible to realize twisting appropriatefor the specifications of various kinds of electric wires.

According to the twisting device 1, it is possible to transmit thedriving force of the first motor 3 a to the first and second gears 16and 17 simultaneously via the driving gear 14. Therefore, it is notnecessary to prepare a driving source for driving the first gear 16 anda driving source for driving the second gear 17 individually.

However, the electric wires C1 and C2 have restoring force. Whenrevolution only is performed when twisting the electric wires C1 and C2,force acts in a direction (that is, a direction of undoing the twistingby revolution) opposite to the revolution direction. Due to this, thetightening of the electric wires C1 and C2 decreases. However, accordingto the twisting device 1, the rotating step S2 as well as the revolvingstep S3 are performed. The rotation direction in the rotating step S2 isopposite to the revolution direction in the revolving step S3.Therefore, it is possible to cancel the force acting on the electricwires C1 and C2 (that is, the force where the electric wires C1 and C2restore to an original state from the twisted state). Due to this, it ispossible to suppress a decrease of the tightening of the electric wiresC1 and C2 in the twisted electric wire CT. According to the twistingdevice 1, it is possible to obtain a suitable twisted electric wire CThaving desired impedance characteristics.

According to the twisting device 1, the third and fourth clamps 2 c and2 d as well as the first and second clamps 2 a and 2 b rotate. Moreover,the second holder 15B as well as the first holder 15A rotates. It ispossible to cause the front ends of both electric wires C1 and C2 torotate and revolve and to cause the rear ends of both electric wires C1and C2 to rotate and revolve. Due to this, it is easy to equalize thetwist pitches P of the twisted electric wire CT. Moreover, it is easy toequalize the residual twisting lengths L at both ends of the twistedelectric wire CT. Furthermore, it is possible to shorten the processingtime as compared to a case in which only the front ends of both electricwires C1 and C2 are caused to rotate and revolve.

According to the twisting device 1, the first and second clamps 2 a and2 b are disposed such that a portion of them come close to the centerline of revolution CL as the portion of them come close to each of thedistal ends. Due to this, it is possible to dispose the front end of thefirst electric wire C1 and the front end of the second electric wire C2near the center line of revolution CL. In this way, it is possible toshorten the residual twisting length L of the front end of the twistedelectric wire CT. Similarly, the third and fourth clamps 2 c and 2 d aredisposed such that a portion of them come close to the center line ofrevolution CL as the portion of them come close to each of the distalends. Due to this, it is possible to dispose the rear end of the firstelectric wire C1 and the rear end of the second electric wire C2 nearthe center line of revolution CL. In this way, it is possible to shortenthe residual twisting length L of the rear end of the twisted electricwire CT.

According to the twisting device 1, the first and second motors 3 a and3 b are located forward of the first and second clamps 2 a and 2 b. Thefirst and second motors 3 a and 3 b are arranged in the directionperpendicular to the center line of revolution CL. The third and fourthmotors 3 c and 3 d are located rearward of the third and fourth clamps 2c and 2 d. The third and fourth motors 3 c and 3 d are arranged in thedirection perpendicular to the center line of revolution CL. Due tothis, it is possible to simplify the configuration of the twistingdevice 1 and to decrease the size thereof.

In the present embodiment, before the first to fourth clamps 2 a to 2 dare caused to revolve in the revolving step S3, the first to fourthclamps 2 a to 2 d are caused to rotate in a direction opposite to therevolution direction in the rotating step S2. With this rotation, thefirst and second electric wires C1 and C2 are twisted in the directionopposite to the revolution direction in advance. Therefore, restoringforce occurs in the first and second electric wires C1 and C2 such thatthe first and second electric wires C1 and C2 return in the revolutiondirection. The restoring force acts as such force that the first andsecond electric wires C1 and C2 are tightened each other when the firstto fourth clamps 2 a to 2 d are caused to revolve. Therefore, accordingto the present embodiment, the tightening of the first and secondelectric wires C1 and C2 increases and a gap is not easily formedbetween the first and second electric wires C1 and C2. Therefore, it ispossible to obtain a satisfactory twisted electric wire CT havingdesired impedance characteristics.

When the second motor 3 b is driven after driving the first motor 3 a,twisting of the first and second electric wires C1 and C2 starts, andthe force of revolution of the first and second clamps 2 a and 2 bpropagates sequentially from the front ends of the first and secondelectric wires C1 and C2 toward the central portions thereof. Similarly,when the fourth motor 3 d is driven after driving the third motor 3c,twisting of the first and second electric wires C1 and C2 starts, andthe force of revolution of the third and fourth clamps 2 c and 2 dpropagates sequentially from the rear ends of the first and secondelectric wires C1 and C2 toward the central portions thereof. As aresult, the residual twisting lengths L of the front end and the rearend of the twisted electric wire CT are equalized and the twist pitchesP thereof are equalized.

As illustrated in FIGS. 12 and the like, starting the rotating step S4after starting the revolving step S3 makes it possible to adjust theresidual twisting length L of the twisted electric wire CT. In thepresent embodiment, since the first to fourth clamps 2 a to 2 d arerotated in the direction opposite to the revolution direction in therotating step S4, it is possible to decrease the residual twistinglength L of the twisted electric wire CT. Therefore, it is possible tosuppress an increase in characteristic impedance of the twisted electricwire CT and to easily control the characteristic impedance to be withina desired range. Therefore, it is possible to obtain a satisfactorytwisted electric wire CT.

Modification of First Embodiment

Hereinabove, the twisting device 1 according to the first embodiment hasbeen described. However, the twisting device 1 is an example only andvarious other modifications may be considered. Next, severalmodifications will be described.

In the embodiment described above, although the gear 13 is interposedbetween the gear 18 and the driving gear 14, it is not particularlylimited thereto. The gear 18 and the driving gear 14 may be directlyengaged with each other. Moreover, a power transmission memberinterposed between the first motor 3 a and the driving gear 14 is notlimited to the gear but may be a power transmission belt, a chain, orthe like. The first motor 3 a and the driving gear 14 may be connecteddirectly.

The rotating actuator and the revolving actuator are not necessarilylimited to motors. The first to fourth motors 3 a to 3 d may be otheractuators that generate driving force. For example, an air cylinder orthe like can be used as the other actuators.

In the embodiment described above, the first and second gripping devices11 and 12 grip the front ends and the rear ends of the first and secondelectric wires C1 and C2, respectively. However, the front and rear usedin the above description are directions determined for the sake ofconvenience only. The first and second gripping devices 11 and 12 may beconfigured to grip the rear ends and the front ends of the first andsecond electric wires C1 and C2, respectively.

In the embodiment described above, the first gripping device 11 executesboth rotation and revolution of the first and second electric wires C1and C2. The second gripping device 12 executes both rotation andrevolution of the first and second electric wires C1 and C2. However,the second gripping device 12 may not execute rotation of the first andsecond electric wires C1 and C2 and may not execute revolution thereof.For example, the third and fourth clamps 2 c and 2 d may be configuredto be non-rotatable. The second holder 15B may be configured to benon-rotatable.

In the embodiment described above, the rear end of the first electricwire C1 is gripped by the third clamp 2 c and the rear end of the secondelectric wire C2 is gripped by the fourth clamp 2 d. However, the rearend of the first electric wire C1 and the rear end of the secondelectric wire C2 may be gripped by the same clamp. That is, the rearends of two electric wires C1 and C2 may be gripped simultaneously byone clamp.

The twisting device 1 according to the embodiment described above isconfigured to twist two electric wires C1 and C2. However, the electricwire twisting device according to the present invention may beconfigured to twist three or more electric wires. In this case, thefirst clamp 2 a, the gear 16, and the like may be provided in three ormore sets.

In the embodiment described above, although all of the first to fourthclamps 2 a to 2 d are inclined with respect to the center line ofrevolution CL, at least one of the first to fourth clamps 2 a to 2 d maybe parallel to the center line of revolution CL.

As illustrated in FIG. 17, the first to fourth clamps 2 a to 2 d may bedisposed in parallel to the center line of revolution CL. In this case,the shafts 20 of the first to fourth clamps 2 a to 2 d are disposed inparallel to the center line of revolution CL. That is, a center line ofrotation (a first center line of rotation) of the first clamp 2 a, acenter line of rotation (a second center line of rotation) of the secondclamp 2 b, a center line of rotation (a third center line of rotation)of the third clamp 2 c,a center line of rotation (a fourth center lineof rotation) of the fourth clamp 2 d,and the center line of revolutionare parallel to each other. A spur gear can be used as the driving gear14, the first gear 16, and the second gear 17.

As schematically illustrated in FIG. 18, in the embodiment describedabove, the first and second clamps 2 a and 2 b are provided in the firstgripping device 11, and the third and fourth clamps 2 c and 2 d areprovided in the second gripping device 12. Both the first and secondgripping devices 11 and 12 can rotate and all of the first to fourthclamps 2 a to 2 d can rotate. However, the configurations of the firstand second gripping devices 11 and 12 are not particularly limited.Next, a modification in which the first and second gripping devices 11and 12 have different configurations will be described.

As illustrated in FIG. 19, the second gripping device 12 may not includethe third and fourth rotatable clamps 2 c and 2 d and may be configuredto be non-rotatable. In this modification, although the first and secondmotors 3 a and 3 b are provided, the third and fourth motors 3 c and 3 dare not necessary. The revolving step S3 is performed when the firstgripping device 11 rotates, and the rotating steps S2 and S4 areperformed when the first and second clamps 2 a and 2 b rotate. Accordingto this modification, a rotating mechanism is not required in the secondgripping device 12. Therefore, it is possible to simplify theconfiguration of the second gripping device 12. The second grippingdevice 12 may include a single clamp that grips both the first andsecond electric wires C1 and C2. When both electric wires C1 and C2 aregripped by a single clamp, a gripping position of the first electricwire C1 and a gripping position of the second electric wire C2 by thesecond gripping device 12 can approach each other more closely.Therefore, it is possible to further shorten the residual twistinglength of the twisted electric wire CT at the position closer to thesecond gripping device 12.

In a reference example illustrated in FIG. 20, although the firstgripping device 11 includes the first and second rotatable clamps 2 aand 2 b, the first gripping device 11 is configured to be non-rotatable.The second gripping device 12 does not include the third and fourthrotatable clamps 2 c and 2 d and is configured to be rotatable. In thisexample, a motor that rotates the first and second clamps 2 a and 2 band a motor that rotates the second gripping device 12 may be included.The revolving step S3 is performed when the second gripping device 12rotates. The rotating steps S2 and S4 are performed when the first andsecond clamps 2 a and 2 b rotate. According to this example, it is notnecessary for one gripping device to include a mechanism for revolutionand a mechanism for rotation. Due to this, it is possible to simplifythe configuration of the first and second gripping devices 11 and 12. Inthis example, the second gripping device 12 may include a single clampthat grips both the first and second electric wires C1 and C2. In thisexample, it is possible to shorten the residual twisting length of thetwisted electric wire CT at the position closer to the second grippingdevice 12.

In the embodiment described above, although the rotating step S2 isperformed, the rotating step S2 is not necessary and can be omitted. Therotating step S4 is not necessary and can be omitted.

In the embodiment described above, although the collecting step S5 isperformed after the rotating step S4 is performed (see FIG. 7), anotherrevolving step may be performed between the rotating step S4 and thecollecting step S5. That is, after adjusting the residual twistinglength of the twisted electric wire CT in the rotating step S4, anadditional revolving step may be performed.

In the embodiment described above, in order to shorten the residualtwisting length of the twisted electric wire CT, both electric wires C1and C2 are rotated in the direction opposite to the revolution directionin the rotating step S4. However, the rotating step S4 may be used forincreasing the residual twisting length as well as shortening theresidual twisting length. The rotating step S4 may be a step of causingboth electric wires C1 and C2 to rotate in the same direction as therevolution direction.

Second Embodiment

In the first embodiment, the rotating step S2 and the revolving step S3are performed by the pair of gripping units 51 and 52. However, thegripping units 51 and 52 may perform any one of the rotating step S2 andthe revolving step S3 and another pair of gripping units may perform theother step.

For example, as illustrated in FIG. 21, the twisting device 1 mayinclude a third gripping device 11A that grips the front ends of bothelectric wires C1 and C2 and a fourth gripping device 12A that grips therear ends of both electric wires C1 and C2 in addition to the first andsecond gripping devices 11 and 12. The twisting device 1 may furtherinclude a first conveying device 61 that conveys the front ends of bothelectric wires C1 and C2 from the first gripping device 11 to the thirdgripping device 11A and a second conveying device 62 that conveys theother set of ends of both electric wires C1 and C2 from the secondgripping device 12 to the fourth gripping device 12A. The third grippingdevice 11A may include a clamp 2 e that grips the front end of the firstelectric wire C1 and a clamp 2 f that grips the front end of the secondelectric wire C2. The fourth gripping device 12A may include a clamp 2 gthat grips the rear end of the first electric wire C1 and a clamp 2 hthat grips the rear end of the second electric wire C2. Actuators (notillustrated) configured as a motor or the like are connected to thethird and fourth gripping devices 11A and 12A, respectively. In thepresent embodiment, the rotating step S2 is performed when the first tofourth clamps 2 a to 2 d rotate and the revolving step S3 is performedwhen the third and fourth gripping devices 11A and 12A rotate.

In the present embodiment, a conveying step is performed after therotating step S2 is performed. In the conveying step, the firstconveying device 61 receives the front ends of both electric wires C1and C2 from the first gripping device 11 and the second conveying device62 receives the rear ends of both electric wires C1 and C2 from thesecond gripping device 12. The first conveying device 61 moves towardthe third gripping device 11A and the second conveying device 62 movestoward the fourth gripping device 12A. After that, the first conveyingdevice 61 delivers the front end of the first electric wire C1 to theclamp 2 e and delivers the front end of the second electric wire C2 tothe clamp 2 f. The second conveying device 62 delivers the rear end ofthe first electric wire C1 to the clamp 2 g and delivers the rear end ofthe second electric wire C2 to the fourth clamp 2 h.

After the conveying step is performed, the third and fourth grippingdevices 11A and 12A perform the revolving step S3. That is, the thirdand fourth gripping devices 11A and 12A rotate and the first and secondelectric wires C1 and C2 are twisted.

According to the present embodiment, the rotating step S2 and therevolving step S3 are performed in separate places. Due to this,although the revolving step S3 is performed subsequently to the rotatingstep S2 in a processing order, the rotating step S2 and the revolvingstep S3 may be performed simultaneously. Rotation of one set of electricwires C1 and C2 and revolution of another set of electric wires C1 andC2 can be performed simultaneously. When twisting of a plurality of setsof electric wires C1 and C2 is performed successively, it is possible toperform the rotating step S2 and the revolving step S3 stably and toshorten the entire processing time. Therefore, it is possible to improvethe production efficiency of the twisted electric wires CT.

The third gripping device 11A may include a single clamp that grips thefront ends of the first and second electric wires C1 and C2 instead ofthe clamps 2 e and 2 f. The fourth gripping device 12A may include asingle clamp that grips the rear ends of the first and second electricwires C1 and C2 instead of the clamps 2 g and 2 h.

In the first embodiment, both the revolving step S3 and the rotatingstep S4 are performed by the pair of gripping units 51 and 52. However,the revolving step S3 and the rotating step S4 may be performed bydifferent gripping units.

As illustrated in FIG. 22, the twisting device 1 may include a grippingdevice 11B that grips one set of ends of both electric wires C1 and C2and a gripping device 12B that grips the other set of ends of bothelectric wires C1 and C2 in addition to the first and second grippingdevices 11 and 12. The twisting device 1 may further include a firstconveying device 61 that conveys one set of ends of both electric wiresC1 and C2 from the gripping device 11B to the first gripping device 11and a second conveying device 62 that conveys the other set of ends ofboth electric wires C1 and C2 from the gripping device 12B to the secondgripping device 12. The gripping devices 11B and 12B are configured tobe rotatable. The twisting device 1 includes a motor (not illustrated)that drives the gripping devices 11B and 12B.

In the twisting device 1 illustrated in FIG. 22, the rotating step S2 isnot performed. The revolving step S3 is performed when the grippingdevices 11B and 12B rotate.

A conveying step is performed after the revolving step S3 is performed.In the conveying step, the first conveying device 61 receives one set ofends of both electric wires C1 and C2 from the gripping device 11B andthe second conveying device 62 receives the other set of ends of bothelectric wires C1 and C2 from the gripping device 12B. The firstconveying device 61 moves toward the first gripping device 11 and thesecond conveying device 62 moves toward the second gripping device 12.After that, the first conveying device 61 delivers one end of the firstelectric wire C1 to the first clamp 2 a and delivers one end of thesecond electric wire C2 to the second clamp 2 b. The second conveyingdevice 62 delivers the other end of the first electric wire C1 to thethird clamp 2 c and delivers the other end of the second electric wireC2 to the fourth clamp 2 d.

After the conveying step is performed, the rotating step S4 is performedby the first and second gripping devices 11 and 12. That is, the firstto fourth clamps 2 a to 2 d rotate and the residual twisting length ofthe twisted electric wire CT is adjusted.

According to the present embodiment, the revolving step S3 and therotating step S4 are performed in separate places. Due to this, althoughthe rotating step S4 is performed subsequently to the revolving step S3in a processing order, the revolving step S3 and the rotating step S4may be performed simultaneously. Revolution of one set of electric wiresC1 and C2 and rotation of another set of electric wires C1 and C2 can beperformed simultaneously. Therefore, when twisting of a plurality ofsets of electric wires C1 and C2 is performed successively, it ispossible to perform the rotating step S4 stably and to shorten theentire processing time.

In the revolving step S3, it is sufficient to rotate at least one of thegripping devices 11B and 12B, and it is not necessary to rotate both. Inthe rotating step S4, it is sufficient to rotate at least one of thefirst and third clamps 2 a and 2 c and at least one of the second andfourth clamps 2 b and 2 d, and it is not necessary to rotate all of thefirst to fourth clamps 2 a to 2 d.

For example, as illustrated in FIG. 23, the gripping device 12B may beconfigured to be non-rotatable. The second gripping device 12 may notinclude the third and fourth rotatable clamps 2 c and 2 d.

In the embodiment described above, although the first conveying device61 that conveys one set of ends of both electric wires C1 and C2 fromthe gripping device 11B to the first gripping device 11 and the secondconveying device 62 that conveys the other set of ends of both electricwires C1 and C2 from the gripping device 12B to the second grippingdevice 12 are included. However, the first conveying device 61 and thefirst gripping device 11 may be omitted, and alternatively, the secondconveying device 62 and the second gripping device 12 may be omitted.For example, in the configuration illustrated in FIG. 22 or 23, thesecond conveying device 62 and the second gripping device 12 may beomitted. In this case, in the conveying step subsequent to the revolvingstep S3, although the first conveying device 61 delivers one set of endsof both electric wires C1 and C2 from the gripping device 11B to thefirst gripping device 11, the gripping device 12B continues gripping theother set of ends of both electric wires C1 and C2. In the rotating stepS4 subsequent to the conveying step, the first and second clamps 2 a and2 b of the first gripping device 11 rotate and the residual twistinglength of the twisted electric wire CT is adjusted.

Although the description is omitted, various modifications similar tothose of the first embodiment may occur in the second embodiment.

Third Embodiment

The twisting device 1 may include another device in addition to theabove-described structure. The twisting device 1 according to the thirdembodiment includes a pitch measuring device 90 that measures thetwisting pitch (a twist pitch) of the twisted electric wire CT. That is,the twisting device 1 according to the third embodiment produces atwisted electric wire CT by twisting the first and second electric wiresC1 and C2 and then measures the twist pitch of the twisted electric wireCT.

In the twisting device 1 according to the third embodiment, the pitchmeasuring device 90 to be described later is applied to the twistingdevice 1 according to the first or second embodiment (including themodifications thereof). However, the twisting device in which the pitchmeasuring device 90 is included is not limited to the twisting device 1described above. In the following description, the pitch measuringdevice 90 provided in a twisting device 1A different from the twistingdevice 1 described above will be described.

In the following description, the directions indicated by symbols F, Rr,L, R, U, and D in the drawings indicate the front, rear, left, right,up, and down unless particularly stated otherwise. However, thesedirections are determined for the sake of convenience only.

As illustrated in FIG. 24, the twisting device 1A includes a firstgripping device 330, a second gripping device 340, a motor 110 thatcauses the first gripping device 330 to rotate around the center line ofrevolution CL, and a motor 120 that causes the second gripping device340 to rotate around the center line of revolution CL. Moreover, thetwisting device 1A includes the pitch measuring device 90, a rail 130,and a conveying unit 140. The pitch measuring device 90 includes amoving unit 150, a pitch sensor 160, and a processor 170. The twistingdevice 1A produces a twisted electric wire CT by twisting the first andsecond electric wires C1 and C2 in which a terminal T is pressure-joinedto both ends thereof.

The first gripping device 330 includes a grip arm 132 that holds therear ends of the first and second electric wires C1 and C2 and a clampactuator (not illustrated) that opens and closes the grip arm 132. Amotor, an air cylinder, a hydraulic cylinder, and the like, for example,can be suitably used as the clamp actuator. The second gripping device340 has a configuration similar to the first gripping device 330. Thesecond gripping device 340 includes a grip arm 142 that can be open andclosed and a clamp actuator (not illustrated) that opens and closes thegrip arm 142.

The second gripping device 340 has a slider 121 that is engaged with therail 130. The second gripping device 340 is configured to change thedistance to the first gripping device 330 by moving on the rail 130. Thesecond gripping device 340 is engaged with a ball screw or the likedriven by a motor, for example, so as to slide on the rail 130 by thepower of the motor. In the present embodiment, the second grippingdevice 340 only slides on the rail 130 among the first and secondgripping devices 330 and 340. However, the first gripping device 330only may slide on the rail 130 or both the first and second grippingdevices 330 and 340 may slide on the rail 130. The driving source is notlimited to the motor and the driving force transmission means is notlimited to the ball screw.

The moving unit 150 is disposed between the first and second grippingdevices 330 and 340. The moving unit 150 is engaged with the rail 130.The moving unit 150 can move on the rail 130. The moving unit 150 canmove toward the first gripping device 330 (rearward) and move toward thesecond gripping device 340 (forward). Hereinafter, the moving directionof the moving unit 150 will be denoted by X. In this example, the movingdirection X is a front-rear direction. A belt 153 wound around a pulley151 of a motor 152, for example, is connected to the moving unit 150.The moving unit 150 can slide along the rail 130 according to therotation of the motor 152. In this example, although the moving unit 150is engaged with the rail 130 the same as the rail with which the secondgripping device 340 is engaged, the moving unit 150 may be engaged witha different rail. However, when the moving unit 150 and the secondgripping device 340 are engaged with the same rail 130, it is possibleto reduce the number of components as compared to a case in whichindividual rails are provided.

The pitch sensor 160 is supported by the moving unit 150. The pitchsensor 160 detects the position of the twisted electric wire CT withrespect to the direction Y perpendicular to the direction X. In thisexample, the direction Y is a left-right direction of the twistingdevice 1A. The position of the pitch sensor 160 is adjusted so that thecenter line of rotation (that is, the center line of revolution) CL ofthe first and second gripping devices 330 and 340 passes through adetection region. The twisted electric wire CT is held on the centerline of revolution CL. An optical sensor such as a photoelectric sensoror a laser sensor, for example, is used as the pitch sensor 160. Forexample, a transmissive photoelectric sensor, a reflective photoelectricsensor, or a laser displacement sensor can be ideally used. A proximitysensor, an image sensor, or the like can be used. A magnetic sensor thatsupplies current to the twisted electric wire CT and measures a magneticfield around the twisted electric wire CT may be used.

The motors 110 and 120 are preferably configured as a servo motor so asto be able to detect a rotational position.

The conveying unit 140 is disposed leftward of the pitch measuringdevice 90, for example. The conveying unit 140 includes two conveyingarms 143 and a moving mechanism (not illustrated) that moves theconveying arms 143. The conveying arm 143 has a mechanism similar to thegrip arm 132 or 142. The conveying arm 143 can grip the first and secondelectric wires C1 and C2 simultaneously in a state in which the electricwires are arranged in the left-right direction. The moving mechanism canmove the conveying arm 143 in the left-right direction. The movingmechanism can convey the first and second electric wires C1 and C2 up tothe position of the center line of revolution CL by moving the conveyingarm 143 rightward.

The processor 170 calculates the twist pitch of the twisted electricwire CT on the basis of the surface position of the twisted electricwire CT detected by the pitch sensor 160.

As illustrated in FIG. 25, the twisted electric wire CT has peaks 220Aand troughs 220B. The peaks 220A and the troughs 220B are alternatelyarranged adjacent to each other. Two sets of peaks 220A and troughs 220Bform one cycle of twisting of the twisted electric wire CT. The twistpitch P can be defined as the distance between the peaks 220A of thefirst electric wire CT or the distance between the peaks 220A of thesecond electric wire C2, for example. For example, the positions ofrespective peaks 220A may be detected along a detection line SL and thedistance obtained by summing the distances between two sets of adjacentand successive peaks 220A may be detected as the twist pitch P. Theposition of the detection line SL is not particularly limited. Forexample, the distance between troughs 220B of the first electric wire C1or the distance between troughs 220B of the second electric wire C2 maybe defined as the twist pitch P. Whether the twist pitch P is adequateor not is determined, for example, on the basis of whether the measuredtwist pitches P fall within a predetermined numerical range.Alternatively, whether the twist pitch P is adequate or not isdetermined on the basis of whether an average twist pitch P falls withina predetermined numerical range.

As illustrated in FIG. 24, the pitch sensor 160 according to the presentembodiment is a transmissive photoelectric sensor having a projector 162and a receiver 164. In the following description, the pitch sensor 160will be referred to as a photoelectric sensor 160. The photoelectricsensor 160 determines the presence of an obstacle on the basis ofwhether the receiver 164 receives light emitted by the projector 162.The receiver 164 is connected to an amplifier 166. The amplifier 166outputs a signal when the receiver 164 does not receive light, forexample. Alternatively, the amplifier 166 may output a signal when thereceiver 164 receives light.

The projector 162 and the receiver 164 face each other with the twistedelectric wire CT disposed therebetween. For example, the projector 162is installed above the twisted electric wire CT and the receiver 164 isinstalled below the twisted electric wire CT. In this example, thedirection of an optical axis OA of the photoelectric sensor 160 is avertical direction. However, the vertical relation of the projector 162and the receiver 164 may be reversed. Moreover, the projector 162 andthe receiver 164 may not necessarily be disposed so that the opticalaxis OA is in the vertical direction. For example, the projector 162 andthe receiver 164 may be disposed so that the optical axis OA is inclinedfrom the vertical direction. The photoelectric sensor 160 detects theposition of the twisted electric wire CT while moving in the directionX. The photoelectric sensor 160 detects a portion of the twistedelectric wire CT positioned on the detection line SL (see FIG. 25) whichis separated by a predetermined distance in a radial direction r fromthe center of the twisted electric wire CT. If the twisted electric wireCT is twisted at a constant pitch, the amplifier 166 of thephotoelectric sensor 160 outputs a signal at a constant interval. Thissignal is input to the processor 170, and the processor 170 calculatesthe twist pitch.

When a light transmissive sensor like the present embodiment is used, aregion SA1 (see FIG. 25) in which both the first electric wire C1 andthe second electric wire C2 are not present on the detection line SL isdetected. On the other hand, when a reflective displacement sensor suchas a laser displacement sensor, for example, is used, the center line CLis used as a detection line and the respective portions of the first andsecond electric wires C1 and C2 are detection targets. When an opticalsensor that emits light in a strip-like shape perpendicular to themoving direction X of the moving unit 150 is used, a region SA3including a region in which the first or second electric wire C1 or C2is present and a region in which both the first and second electricwires C1 and C2 are not present is a detection target.

Next, an operation of the twisting device 1A will be described. First,the conveying arm 143 of the conveying unit 140 moves rightward whilegripping the first and second electric wires C1 and C2. Subsequently,the conveying arm 143 delivers the first and second electric wires C1and C2 to the first and second gripping devices 330 and 340.

Subsequently, the motor 110 rotates the first gripping device 330 andthe motor 120 rotates the second gripping device 340. The rotationdirection of the first gripping device 330 is opposite to the rotationdirection of the second gripping device 340. With rotation of the firstand second gripping devices 330 and 340, the first and second electricwires CT are twisted. When the first and second electric wires C1 and C2are twisted, an apparent length decreases. Therefore, the secondgripping device 340 moves toward the first gripping device 330 with theprogress of twisting. The second gripping device 340 may move at apredetermined speed or may move so that the tension of the first andsecond electric wires C1 and C2 becomes constant.

In this way, the twisted electric wire CT is produced. When the twistedelectric wire CT is produced, the motors 110 and 120 stop and therotation of the first and second gripping devices 330 and 340 stop.Subsequently, the moving unit 150 moves from one of the first and secondgripping devices 330 and 340 toward the other gripping device and thepitch sensor 160 measures the position of the twisted electric wire CT.The processor 170 receives a signal from the pitch sensor 160 andcalculates the twist pitch of the twisted electric wire CT. Moreover,the processor 170 determines whether the quality of the twisted electricwire CT is satisfactory on the basis of whether the twist pitch iswithin a predetermined numerical range.

According to the pitch measuring device 90 of the present embodiment,the moving unit 150 moves in the longitudinal direction of the twistedelectric wire CT in a state in which the first and second grippingdevices 330 and 340 hold the ends of the first and second electric wiresC1 and C2. When the moving unit 150 moves, the twist pitch of thetwisted electric wire CT is measured. Due to this, it is not necessaryto cut the ends of the twisted electric wire CT and pressure-joint theterminal T to the ends after the twist pitch is measured. Therefore,there is no possibility that the quality of the twisted electric wire CTdeteriorates after the pitch measurement. Moreover, the twist pitch iscalculated on the basis of the surface position of the twisted electricwire CT detected by the pitch sensor 160. Due to this, it is possible tomeasure the pitch with high accuracy. Therefore, according to the pitchmeasuring device 90, it is possible to perform high-accuracy pitchmeasurement and to maintain the quality of the twisted electric wire CTafter the measurement.

However, a variation may occur in the gripping position of the first andsecond electric wires C1 and C2 by the first and second gripping devices330 and 340. For example, as illustrated in FIG. 26, the first grippingdevice 330 may hold one set of ends of the first and second electricwires C1 and C2 on the right of the center line of revolution CL, andthe second gripping device 340 may hold the other set of ends of thefirst and second electric wires C1 and C2 on the left of the center lineof revolution CL. In this case, when the first and second grippingdevices 330 and 340 are rotated, the twisted electric wire CT is tiltedfrom the center line of revolution CL when seen from the above. When thetwisted electric wire CT is tilted in this manner, an error may occur inthe pitch measured by the photoelectric sensor 160.

Therefore, the first and second gripping devices 330 and 340 (see FIGS.24 and 26) oriented horizontally when receiving the first and secondelectric wires C1 and C2 may be oriented vertically when measuring thepitch as illustrated in FIG. 27. The first and second gripping device330 and 340 being oriented vertically refers to a state in which agripping surface 135 of the grip arm 132 and a gripping surface 145 ofthe grip arm 142 are oriented vertically. On the other hand, the firstand second gripping devices 330 and 340 being oriented horizontallyrefers to a state in which the gripping surfaces 135 and 145 areoriented horizontally. In this manner, before the pitch measurement, theposition of the first and second gripping devices 330 and 340 may bechanged by 90° from a position wherein the first and second grippingdevices receive the first and second electric wires C1 and C2 from theconveying arm 143. In this way, as illustrated in FIG. 27, the twistedelectric wire CT is positioned on the center line of revolution CL whenseen from the above. When the first and second gripping devices 330 and340 are oriented vertically in this manner, the twisted electric wire CTis held within a vertical plane including the optical axis OA of thephotoelectric sensor 160 and the moving direction X of the moving unit150 or within a vertical plane parallel to the vertical plane. Due tothis, it is possible to perform the pitch measurement by thephotoelectric sensor 160 satisfactorily regardless of the shift in thegripping position.

When the twisted electric wire CT is disposed within a plane thatincludes the optical axis OA of the photoelectric sensor 160 and isparallel to the moving direction X of the moving unit 150, although thefirst and second gripping devices 330 and 340 may be rotated around thecenter line of revolution CL, the photoelectric sensor 160 may berotated around the center line of revolution CL. In the presentembodiment, the motor 110 is configured to rotate the first grippingdevice 330 and the motor 120 is configured to rotate the second grippingdevice 340. Due to this, a dedicated rotating mechanism for disposingthe twisted electric wire CT within the plane is not necessary. However,a dedicated rotating mechanism may be provided in the first and secondgripping devices 330 and 340 or the photoelectric sensor 160. In orderto dispose the twisted electric wire CT in the plane, a rotatingmechanism may be provided in addition to the motors 110 and 120.

The photoelectric sensor 160 may be configured to emit linear light andmay be configured to emit strip-like light. When the photoelectricsensor 160 that emits light having a strip-like shape perpendicular tothe moving direction X of the moving unit 150 is used, light of whichthe optical axis extends in a vertical direction is emitted continuouslyin a strip-like form in the direction Y. FIG. 28 is a perspective viewof the pitch measuring device 90 including the photoelectric sensor 160that emits the strip-like light. A symbol SA in FIG. 28 indicates adetection region of the photoelectric sensor 160. This detection regionSA has a width in the direction Y.

FIG. 29 is a schematic top view of the pitch measuring device 90illustrated in FIG. 28. As illustrated in FIG. 29, even when the twistedelectric wire CT is tilted from the center line of revolution CL whenseen from the above, since the detection region SA of the photoelectricsensor 160 has a width in the direction Y, all portions of the twistedelectric wire CT falls within the detection region SA. Therefore, evenwhen the first and second gripping devices 330 and 340 are not rotatedor the photoelectric sensor 160 is not rotated, it is possible toperform the pitch measurement by the photoelectric sensor 160satisfactorily. Furthermore, in this example, since the first and secondgripping devices 330 and 340 are oriented horizontally, all portions ofthe twisted electric wire CT fall within the same horizontal plane HP.Due to this, the distances between the projector 162 and the respectiveportions of the twisted electric wire CT become equal and the distancesbetween the receiver 164 and the respective portions of the twistedelectric wire CT become equal. Therefore, it is possible to perform thepitch measurement by the photoelectric sensor 160 more satisfactorily.In this example, since the first and second gripping devices 330 and 340are oriented horizontally, all portions of the twisted electric wire CTare disposed within the same plane perpendicular to the optical axis ofthe photoelectric sensor 160. However, if not, the pitch measuringdevice 90 may include a mechanism for rotating the first and secondgripping devices 330 and 340 or rotating the moving unit 150 so that thetwisted electric wire CT is disposed within the same plane perpendicularto the optical axis of the photoelectric sensor 160.

In the embodiment described above, one pitch sensor 160 is providedbetween the first and second gripping devices 330 and 340. However, aplurality of pitch sensors 160 may be provided between the first andsecond gripping devices 330 and 340. For example, as illustrated in FIG.30, three pitch sensors 160 may be provided between the first and secondgripping devices 330 and 340. A number of moving units 150 the same asthe number of pitch sensors 160 are engaged with the rail 130. Therespective pitch sensors 160 are supported by the moving units 150engaged with the rail 130.

When a plurality of pitch sensors 160 is provided, a measurement rangeper one pitch sensor 160 in the longitudinal direction of the twistedelectric wire CT can be decreased. Therefore, it is possible to shortenthe time for measuring the pitch of the twisted electric wire CT. Forexample, when three pitch sensors 160 are provided, the pitchmeasurement time can be shorted by ⅓.

In the embodiment described above, the conveying arm 143 is configuredto deliver the first and second electric wires C1 and C2 to the firstand second gripping devices 330 and 340 from a lateral side. However,depending on the type of the twisting device 1A, the conveying arm 143may deliver the first and second electric wires C1 and C2 to the firstand second gripping devices 330 and 340 from the upper side toward thelower side. In this case, the pitch sensor 160 may become an obstacle.

As illustrated in FIG. 24, a collection tray 155 may be disposed belowthe first and second gripping devices 330 and 340 and the pitch sensor160. In this case, after the pitch of the twisted electric wire CT ismeasured, the twisting device 1A opens the first and second grippingdevices 330 and 340 so that the twisted electric wire CT falls freely tobe collected in the collection tray 155. In this case, the pitch sensor160 may become an obstacle.

Therefore, as illustrated in FIG. 31, the sensor attachment member 250to which the pitch sensor 160 is attached may be configured to bemovable between a detection position SP and an evacuation position EP.Although the configuration of the sensor attachment member 250 is notparticularly limited, the sensor attachment member 250 includes anattachment plate 252 and a hinge 254. The attachment plate 252 isconfigured to be rotatable about a vertical axis. The projector 162 andthe receiver 164 are attached to the attachment plate 252. A position atwhich the attachment plate 252 faces the direction Y is the detectionposition SP and a position at which the attachment plate 252 faces thedirection X is the evacuation position EP. When the attachment plate 252is at the detection position SP, the attachment plate 252 overlaps thetwisted electric wire CT when seen from the above. When the attachmentplate 252 is at the detection position SP, the twisted electric wire CTis positioned between the projector 162 and the receiver 164. On theother hand, when the attachment plate 252 is at the evacuation positionEP, the attachment plate 252 does not overlap the twisted electric wireCT when seen from the above. When the attachment plate 252 is at theevacuation position EP, the twisted electric wire CT is not disposedbetween the projector 162 and the receiver 164.

According to the present embodiment, when the pitch of the twistedelectric wire CT is not measured, the sensor attachment member 250 ismoved to the evacuation position EP whereby the pitch sensor 160 and thesensor attachment member 250 are prevented from becoming an obstacle.That is, when the first and second electric wires C1 and C2 aredelivered to the first and second gripping devices 330 and 340 from theupper side toward the lower side, or when the first and second grippingdevices 330 and 340 are open so that the twisted electric wire CT fallsfreely, it is possible to prevent the pitch sensor 160 and the sensorattachment member 250 from becoming an obstacle. Moreover, it ispossible to prevent the first and second electric wires C1 and C2 frommaking contact with the pitch sensor 160 or the sensor attachment member250 when the first and second gripping devices 330 and 340 are rotated.

Although the sensor attachment member 250 may be moved manually by auser, an actuator 260 may be provided so as to move the sensorattachment member 250 between the detection position SP and theevacuation position EP. The actuator 260 is an air cylinder, an electricmotor, or the like, for example. For example, an air cylinder having ashaft connected to the attachment plate 252 may be used. The actuator260 may be controlled so as to be interlocked with at least one of theconveying unit 140, the first gripping devices 330 and 340, and themotors 110 and 120.

An evacuation detection sensor that detects whether the sensorattachment member 250 is at the evacuation position EP may be provided.By detecting the position of the sensor attachment member 250, it ispossible to prevent the first and second electric wires C1 and C2 frombeing conveyed to the first and second gripping devices 330 and 340 fromthe upper side toward the lower side and to prevent the twisted electricwire CT from falling toward the collection tray 155 in a state in whichthe sensor attachment member 250 is at the detection position SP.Whether the sensor attachment member 250 is at the evacuation positionEP can be ascertained by the naked eyes. However, by using theevacuation detection sensor, it is possible to detect that the sensorattachment member 250 is at the evacuation position EP more reliably.

Various control operations can be performed using a signal output by theevacuation detection sensor. For example, when the conveying unit 140conveys the electric wires C1 and C2 toward the first gripping devices330 and 340 in a state in which the sensor attachment member 250 is atthe detection position SP, the operation of the conveying unit 140 maybe forcibly stopped according to the signal output by the evacuationdetection sensor. The first and second gripping devices 330 and 340 maybe caused so as not to release the twisted electric wire CT when thesensor attachment member 250 is at the detection position SP using thesignal output by the evacuation detection sensor.

The configuration of the evacuation detection sensor is not particularlylimited. The evacuation detection sensor is a proximity switch includedin the actuator 260, for example. For example, by using an air cylinderwith a proximity switch, it is possible to detect a position at whichthe shaft of the air cylinder is retracted and a position at which theair cylinder is extended. Moreover, as illustrated in FIG. 31, a limitswitch 270 may be disposed at a position at which the limit switch 270is pressed by the attachment plate 252 when the sensor attachment member250 is folded to the evacuation position EP.

Although a dedicated sensor may be provided as the evacuation detectionsensor, the pitch sensor 160 may be used as the evacuation detectionsensor. For example, as illustrated in FIG. 32, a shielding plate 280may be provided so as to block light traveling from the projector 162toward the receiver 164 when the sensor attachment member 250 is at theevacuation position EP so that the detection state of the pitch sensor160 is different depending on whether the sensor attachment member 250is at the detection position SP or the evacuation position EP. In thisway, it is not necessary to provide an evacuation detection sensor apartfrom the pitch sensor 160. Therefore, it is possible to decrease thenumber of components of the twisting device 1A.

By using the pitch sensor 160, it is possible to detect whether thefirst and second electric wires C1 and C2 are disposed between the firstand second gripping devices 330 and 340. In other words, by using thesignal output from the pitch sensor 160, it is possible to detectwhether the first and second electric wires C1 and C2 are held by thefirst and second gripping devices 330 and 340 before the first andsecond electric wires C1 and C2 are twisted. Moreover, it is possible todetect whether the twisted electric wire CT is held by the first andsecond gripping devices 330 and 340 after the first and second electricwires C1 and C2 are twisted.

The twisting device 1A may include a determination device 190 (see FIG.24) that determines whether the twisted electric wire CT is held by thefirst and second gripping devices 330 and 340 on the basis of the signaloutput from the pitch sensor 160 before or after the moving unit 150 ismoved. The determination device 190 receives a signal from the pitchsensor 160 and determines whether the twisted electric wire CT isactually held at a position at which the twisted electric wire CT is tobe held. For example, this determination is made by determining whetheran obstacle is present in a detection region of the photoelectric sensor160. When the twisted electric wire CT is not present between the firstand second gripping devices 330 and 340, light from the projector 162 isnot blocked at any position of the detection region but light isreceived at all positions. When the determination device 190 determinesthat the twisted electric wire CT is not held, a process of stopping thetwisting device 1A, a process of issuing a warning, or the like may beperformed.

In the twisting device 1A, the first gripping device 330 is configuredto grip one set of ends of the first and second electric wires C1 andC2, and the second gripping device 340 is configured to grip the otherset of ends of the first and second electric wires C1 and C2. Theconveying unit 140 is configured to deliver one set of ends of the firstelectric wires C1 and C2 to the first gripping device 330 simultaneouslyand deliver the other set of ends of the first and second electric wiresC1 and C2 to the second gripping device 340 simultaneously. However, thefirst gripping device 330 may be configured to grip one end of the firstelectric wire C1 and one end of the second electric wire C2individually. The second gripping device 340 may be configured to gripthe other end of the first electric wire C1 and the other end of thesecond electric wire C2 individually. The conveying unit 140 may beconfigured to convey the first and second electric wires C1 and C2individually.

The pitch measurement may be performed for all twisted electric wires CTproduced by the twisting device 1A and may be performed for only some ofthe twisted electric wires CT produced successively. For example, thepitch measurement may be performed for a predetermined number of twistedelectric wires CT immediately after startup of the twisting device 1A(initial inspection). Alternatively, the pitch measurement may beperformed for a predetermined number of twisted electric wires CT atevery predetermined intervals during operation of the twisting device 1A(periodic inspection). The pitch measurement may be performed when auser has instructed to do so. The pitch measurement can be executed atan arbitrary timing.

Hereinabove, the pitch measuring device 90 provided in the twistingdevice 1A has been described. As described above, the twisting device 1according to the third embodiment is configured such that the pitchmeasuring device 90 is added to the twisting device 1 according to thefirst or second embodiment. For example, it is possible to obtain thetwisting device 1 including the pitch measuring device 90 by replacingthe first and second gripping devices 330 and 340, the motors 110 and120, the rail 130, and the slider 121 of the twisting device 1A with thefirst and second gripping devices 11 and 12, the first and second motors3 a and 3 b, the rail 4, and the base 5 of the first gripping unit 51 ofthe twisting device 1, respectively.

REFERENCE SIGNS LIST

-   1 Electric wire twisting device-   2 a First clamp-   2 b Second clamp-   3 a First motor (First rotating actuator)-   3 b Second motor (First revolving actuator)-   15A First holder-   11 First gripping device-   12 Second gripping device-   C1 First electric wire-   C2 Second electric wire-   CT Twisted electric wire-   CL Center line of revolution-   Q1 First center line of rotation-   Q2 Second center line of rotation

The invention claimed is:
 1. An electric wire twisting device producinga twisted electric wire by twisting at least a first electric wire and asecond electric wire each of the first and second electric wires havinga first end and a second end, the electric wire twisting devicecomprising: a first gripping device including a first clamp that gripsthe first end of the first electric wire, a second clamp that grips thefirst end of the second electric wire, and a first holder that holds thefirst clamp and the second clamp; a second gripping device that gripsthe second end of the first electric wire and the second end of thesecond electric wire; a first revolving actuator that is connected tothe first holder so as to cause the first holder to rotate around acenter line of revolution positioned between the first clamp and thesecond clamp; a first rotating actuator that is connected to at leastthe first clamp so as to cause the first clamp to rotate around a firstcenter line of rotation that is parallel to the center line ofrevolution or is inclined with respect to the center line of revolution;a pitch measuring device that measures a pitch of twisting of thetwisted electric wire, wherein the pitch measuring device includes: amoving unit that is located between the first gripping device and thesecond gripping device and is movable with respect to both of the firstgripping device and the second gripping device along the center line ofrevolution; a sensor that is supported on the moving unit and detects asurface position of the twisted electric wire; and a processor thatcalculates the pitch of twisting of the twisted electric wire based onthe surface position of the twisted electric wire detected by thesensor; and a rail that extends in a direction parallel to the centerline of revolution and configured such that at least one of the firstgripping device and the second gripping device is slidably engaged withthe rail, wherein the moving unit is slidably engaged with the rail. 2.The electric wire twisting device according to claim 1, furthercomprising: a driving gear that rotates by a driving force of the firstrotating actuator; and a first gear that is fixed to the first clamp andengages with the driving gear.
 3. The electric wire twisting deviceaccording to claim 1, wherein the first rotating actuator is configuredto cause the first clamp to rotate in a first rotation direction, andthe first revolving actuator is configured to cause the first holder torotate in a second rotation direction opposite to the first rotationdirection.
 4. The electric wire twisting device according to claim 3,wherein the second gripping device includes a third clamp that grips thesecond end of the first electric wire, a fourth clamp that grips thesecond end of the second electric wire, and a second holder that holdsthe third clamp and the fourth clamp, the electric wire twisting devicefurther including a second revolving actuator that is connected to thesecond holder so as to cause the second holder to rotate in the firstrotation direction.
 5. The electric wire twisting device according toclaim 4, further comprising: a second rotating actuator that isconnected to at least the third clamp so as to cause the third clamp torotate around a third center line of rotation that is parallel to thecenter line of revolution or is inclined with respect to the center lineof revolution, wherein the second rotating actuator is configured tocause the third clamp to rotate in the second rotation direction.
 6. Theelectric wire twisting device according to claim 1, wherein the firstclamp is disposed such that a portion of the first clamp comes close tothe center line of revolution as the portion of the first clamp comesclose to a distal end thereof, and the first center line of revolutionis inclined with respect to the center line of revolution; and/or thesecond clamp is disposed such that a portion of the second clamp comesclose to the center line of revolution as the portion of the secondclamp comes close to a distal end thereof, and the second center line ofrotation is inclined with respect to the center line of revolution. 7.The electric wire twisting device according to claim 1, wherein at leastone of the first and second clamps includes: a shaft which has a distalend and a base end and is slidably and rotatably supported by the firstholder; a grip arm which is connected to the distal end of the shaft sothat the grip arm is open when the shaft slides from the base end towardthe distal end and is closed when the shaft slides from the distal endtoward the base end; a forcing member that is attached to the shaft soas to provide force with the shaft so that the shaft is urged from thedistal end toward the base end; and a clamp actuator that provides forcewith the shaft so that the shaft is urged from the base end to thedistal end.
 8. The electric wire twisting device according to claim 7,wherein the forcing member is a spring, the clamp actuator has anengagement portion that is movable between an engagement position, atwhich the engagement portion engages with the shaft, and a separationposition, at which the engagement portion is separated from the shaft,and a driving source that moves the engagement portion, and theengagement portion engages with the shaft such that force is providedwith the shaft so that the shaft is urged from the base end toward thedistal end.
 9. The electric wire twisting device according to claim 1,further comprising: a controller that starts driving the first rotatingactuator before the first revolving actuator starts driving.
 10. Theelectric wire twisting device according to claim 9, wherein thecontroller starts driving the first rotating actuator after driving ofthe first rotating actuator is stopped temporarily and after the firstrevolving actuator starts driving.
 11. The electric wire twisting deviceaccording to claim 1, further comprising a controller that startsdriving the first rotating actuator after the first revolving actuatorstarts driving.
 12. The electric wire twisting device according to claim1, wherein the second gripping device includes a third clamp that gripsthe second end of the first electric wire, a fourth clamp that grips thesecond end of the second electric wire, and a second holder that holdsthe third clamp and the fourth clamp, the electric wire twisting devicefurther including: a second revolving actuator that is connected to thesecond holder so as to cause the second holder to rotate in the firstrotation direction; and a controller that starts driving the firstrotating actuator after the second revolving actuator starts driving.13. The electric wire twisting device according to claim 1, furthercomprising: a third gripping device including a fifth clamp that gripsthe first end of the first electric wire and a sixth clamp that gripsthe first end of the second electric wire; a third rotating actuatorthat is connected to at least the fifth clamp so as to cause the fifthclamp to rotate around a fifth center line of rotation that is parallelto the center line of revolution or is inclined with respect to thecenter line of revolution; a conveying device that conveys the first endof the first electric wire from the first clamp to the fifth clamp andconveys the first end of the second electric wire from the second clampto the sixth clamp; and a controller that starts driving the thirdrotating actuator after driving the conveying device after the drivingof the first revolving actuator ends.
 14. The electric wire twistingdevice according to claim 1, wherein the sensor is an optical sensor,and the first gripping device, the second gripping device, and themoving unit are configured so that the twisted electric wire is disposedwithin a plane including the center line of revolution and an opticalaxis of the optical sensor or a plane parallel to the plane when theoptical sensor performs detection.
 15. The electric wire twisting deviceaccording to claim 1, wherein the moving unit has a sensor attachmentmember to which the sensor is attached, and the sensor attachment memberis configured to be movable between a detection position at which thesensor detects the surface position of the twisted electric wire and anevacuation position at which the sensor attachment member is evacuatedfrom the detection position.
 16. The electric wire twisting deviceaccording to claim 1, wherein the pitch measuring device measures thepitch of twisting of the twisted electric wire by moving according tothe movement of the moving unit a long the center line of revolution.17. The electric wire twisting device according to claim 1, wherein thepitch measuring device measures the pitch of twisting of the twistedelectric wire after the first revolving actuator stops the rotation ofthe first holder.